Recent studies indicate a key role of Mitf (microphthalmia-associated transcription factor) in the differentiation of the retinal pigment epithelium (RPE). To explore transdifferentiation processes, we used small interfering RNA (siRNA) targeting Mitf. Transfection of embryonic chick RPE cells with a non-silencing fluorescein-labelled control siRNA demonstrated a high (84%) transfection efficiency. Transfection of Mitf siRNA reduced Mitf synthesis at the mRNA and protein levels as analysed by real-time RT-PCR and Western blot. Mitf siRNA suppressed the expression of Mitf RNA to 25.0% of the level in control cells (P
